125kHz 
125kHz RFID Readers
L120-U 125kHz USB RFID Reader, Flat Desktop Pad, EM4100/TK4100
The L120-U is a flat, matte 125 kHz desktop reader for reception desks, attendance points and membership counters where staff enter card numbers into existing software. It reads EM4100 and TK4100 cards and fobs at up to 80 mm and types a 10-digit decimal number over USB, with no driver to install.
- Frequency
- 125 kHz
- Cards / tags
- EM4100, TK4100, SMC4001 and EM4100-compatible cards and key fobs
- Interface
- USB, keyboard emulation
- Output
- 10-digit decimal card number
- Read range
- Up to 80 mm (depends on card and environment)
- ✓ Sample units for evaluation
- ✓ Output format confirmed for your software
- ✓ Private label & OEM options
- ✓ Reply within 1 business day
Why integrators choose the L120-U
- Front-desk friendly — a flat matte pad with the status LED and cable exit on the same top edge.
- Cards and key fobs — EM4100, TK4100 and SMC4001 IDs, the 125 kHz chips common in membership and building fobs.
- Types at the cursor — works as a USB keyboard, so the card number lands in any open field with nothing to install.
- Quick queue handling — read time under 200 ms and a read interval under 0.5 s.
- 1400 mm cable — ends in a standard USB-A plug for PCs and POS terminals.
Built for the front desk
The L120-U suits places where a person checks cards many times a day: a gym or club reception where members carry 125 kHz key fobs, a school office logging late arrivals, or a site office handing out visitor fobs. It lies flat with a matte top. The status LED sits at the top edge and the 1400 mm cable leaves from the same edge, so the reader can sit beside a keyboard without the cable crossing the reading area.
Staff click the search or member field, hold the card or fob over the pad, and the number is typed in. Nothing is installed on the PC, which matters when the front-desk computer is locked down by IT.
Replacing typed card numbers
Many membership and visitor systems were set up with staff typing the number printed on each card. The L120-U reads the number from the chip instead: by default a 10-digit decimal value, which is also the number printed on many EM4100 cards. If your records hold a two-part number (facility code and card number) or hex, a matching custom format can be set before shipment; compare a few of your cards with the card number converter first.
- Hold key fobs closer than cards; their smaller antennas read at shorter distances than the 80 mm maximum.
- If digits come out as symbols, set the host input language to English (US), because keyboard readers send key codes that the active layout interprets.
More fixes are in RFID reader not reading cards?
Flat pad or slim pad?
The L120-U and the L110-U read the same EM4100-family cards with the same range, timing and default output. The difference is the housing: the L120-U is a flat matte pad with its cable leaving the top edge, while the L110-U is a slim pad with the USB connection at one short end. The flat pad is also built as the L120-R for serial hosts and the H120-U for 13.56 MHz cards.
L120-U specifications
| Model | L120-U |
|---|---|
| Frequency | 125 kHz |
| Form factor | Flat matte desktop pad with USB cable |
| Housing | ABS |
| Color | Black |
| Supported cards | EM4100, TK4100, SMC4001 and EM4100-compatible cards and key fobs |
|---|---|
| Card operation | Read-only (card ID number) |
| Read range | Up to 80 mm (depends on card and environment) |
| Read time | < 200 ms |
| Read interval | < 0.5 s |
| Interface | USB, keyboard emulation |
|---|---|
| Driver | Not required |
| Default output | 10-digit decimal card number |
| Output options | Custom output format on request |
| Operating systems | Windows XP / Vista / 7 / 10, Linux, Android |
| Indicators | Red/green LED (red = standby, green = card read) and buzzer |
| Dimensions | 104 × 68 × 10 mm |
|---|---|
| Weight | Approx. 140 g |
| Cable length | 1400 mm |
| Power supply | 5 V DC, USB bus-powered |
| Operating temperature | -10 °C to +70 °C |
| Storage temperature | -20 °C to +80 °C |
| Humidity | < 90 % RH |
Specifications of L120-U as supplied for the standard version. Read range depends on the card or tag, mounting surface and environment — we can test your own cards before you order.
Card, tag and system compatibility
Works with
- ✓EM4100, TK4100 and SMC4001 125 kHz cards
- ✓EM4100-compatible key fobs
- ✓Windows XP, Vista, 7 and 10
- ✓Linux and Android hosts with USB keyboard support
Card not listed? Send us the card type or a photo and we will confirm compatibility before you buy.
Integration in 4 steps
- 1
Plug the USB-A connector into the PC or POS terminal. The reader appears as a keyboard and the LED shows red.
- 2
Click into the member, badge or card field of your software.
- 3
Hold the card over the pad: a beep, a green LED and the 10-digit number typed into the field.
- 4
If the number does not match your records, send us the printed card number and the value your software stores; we set the output format to match before shipment.
OEM / ODM options for L120-U
- ◆Card-number format preset on request, e.g. 8-digit hex or reversed byte order
- ◆Enter or no suffix after the card number, set before shipment
- ◆RS232 version in the same flat housing (L120-R)
- ◆Same housing for 13.56 MHz (H120-U) and UHF (U120-U) readers
- ◆Private-label marking and packaging — scope confirmed in your quotation
Typical applications
L120-U FAQ
Will the L120-U work on a locked-down front-desk PC?
Usually yes, because nothing is installed: it enumerates as a standard USB keyboard on Windows, Linux and Android. If USB keyboards are blocked by policy, IT needs to allow it like any other keyboard.
Why does the typed number differ from the number printed on the card?
Cards are often printed in a different format from the reader output, for example as two numbers (facility code and card number) instead of one 10-digit value. Compare them with the card number converter, or ask us to set the matching format in the reader.
What cable does the L120-U have?
A 1400 mm USB cable ending in a USB-A plug. The reader is powered from the USB port at 5 V DC.
Does the L120-U read key fobs?
Yes, EM4100-compatible key fobs are supported. Fobs have smaller antennas than cards, so hold them closer than the 80 mm maximum.
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125kHz Tell us your card, interface and quantity
Send the card or tag type, the host system and your volume. We reply within 1 business day with a suggested model and sample options.